In today's rapidly advancing semiconductor manufacturing industry, it is critical to increase integration levels to provide increased functionality within a given chip area. Stacked 3D technology represents a favored technology for increasing integration levels by stacking device levels over one another in one integrated unit. The use of thin substrates in the stacking layers enables greater levels of functionality to be utilized within a given space but as the thickness of the stacked substrates decreases, vertical noise between devices on different tiers or levels, manifests itself as an issue that needs to be addressed.
Decoupling capacitors also known as de-caps are devices that decouple electronic noise caused by various signals. Decoupling capacitors reduce noise in semiconductor devices by decoupling one part of an electrical circuit from other parts. Noise caused by other circuit elements is shunted through the capacitor, reducing the effect it has on the rest of the circuit. When decoupling capacitors are positioned in close proximity to circuit elements, they have maximum efficiency in reducing noise but can adversely affect performance by signal loading. In this case, the decoupling capacitors have good power integrity but poor signal integrity. If decoupling capacitors are sacrificed in the device layout to focus on signal integrity, then noise reduction by decoupling capacitors is diminished.
Various ESD (electrostatic discharge) protection devices are also used in the art. Typically ESD protection devices and decoupling capacitors are located outside the periphery of the circuits or circuit blocks that combine to form a circuit. Because decoupling capacitors and other ESD protection devices are formed surrounding the circuit or a block portion of a circuit, they consume surface area either surrounding the entire circuit or the individual blocks of the circuit desired to be protected. The consumption of this space for decoupling capacitors or other ESD protection devices either increases the size of the chip required or comes at the expense of other functional device features.
It would be desirable to provide devices capable of alleviating noise in semiconductor devices and in particular vertical noise in stacked 3D technology semiconductor devices that utilize thin substrates.